The invention relates to the field of band wrapping machines, and particularly to a device for fixing the position of the overlapping, mutually binding ends of bands in the locking block of a machine for automatic binding packages by encircling them with band material.
In known machines of this kind, a part of the band material is introduced into an annular channel surrounding the package that is to be bound around by moving an end of the band up to a stop. The free end of the band is then caught and stretched around the package by retracting it from its feed-in end. The band is held tight after reaching its final tension, and then cut-off from the band supply. The overlapping band ends are then connected, for example, by welding.
In order to obtain a durable and strong connection, it is necessary to align the ends of the band laterally before their connection especially when using a plastic band. The ends must be placed precisely one above the other on the working position of the locking or connecting mechanism, such as a welding head.
It is known to provide stationary guiding channels in the locking block to guide the band ends laterally. However, such solid, lateral band guides have the disadvantage that the locked band has to be removed from the guiding channels transversely to the plane of the band. In order to do this, it is necessary that the counterpressure plate be laterally shiftable out of the range of the band. However, it has now been demonstrated that, when welding plastic bands by means of a supersonic apparatus, the counterpressure plate must be precisely parallel to the end surfaces of the welding head in order to obtain a satisfactory welded connection. Practically, such precise alignment cannot be obtained with a mobile counterpressure plate.
A further disadvantage consists in the fact that stationary guiding channels are devised for a certain band-width and must be replaced in case of a change in the width of the band. The requirement for additional band guides and their installation each time the band width is changed is troublesome and time consuming.